Nutrient - Adequate zinc intake protects DNA

By Holly Taylor BSc (Hons) DipCNM MBANT

Researchers from the US have recently reported, in the American Journal of Clinical Nutrition, that low levels of dietary zinc are associated with an increase in the breakage of the DNA strands in peripheral blood cells, while restoring zinc to normal levels reduces breakage.

Zinc deficiency is estimated to affect two billion people across the world and is believed to elevate the risk of several chronic diseases such as cancer. The ability of zinc to increase DNA repair, in addition to its role as an antioxidant, may be responsible for its protective effects

During the study, nine healthy men were put on a controlled diet so the scientists could manipulate their zinc levels. For the first 13 days the men received a diet that contained 11mg of zinc per day, to ensure adequate zinc status. The subjects then underwent a 42 day zinc depletion. On the 56th day of the study, the participants were switched back to the 11mg per day zinc diet and continued on this diet for 18 days, with the addition of supplemental zinc for the first 7 days of this period. Blood samples were taken at regular time points throughout the study so the blood cells could be analysed for DNA damage.

The results showed that, by the end of the zinc depletion period, DNA strand damage had increased by 57% compared to the beginning of the study. Luckily, this increase in damage proved to be reversible, as blood samples taken from the end of the study, after zinc levels had been restored, showed a 39.9% decrease in strand breakage.

The authors concluded the study by remarking that: “Overall, these data suggest that dietary zinc status affects DNA damage in peripheral blood cells and that adequate zinc status may be essential to maintain DNA integrity in humans.”